It’s tempting to say that the 6% drop in Ctrip.com’s (CTRP) shares on August 10 after the company’s August 9 earnings report was just the usual selling on the news by momentum investors who are unhappy that the company only beat Wall Street estimates by 2 cents a share and didn’t raise guidance for its third quarter.

But when you’re looking at a stock that’s trading at 43.5 times projected 2010 earnings per share, I’m not sure there’s any “just” about an earnings report that didn’t shoot out the lights.

There’s just enough in the numbers to concern any investor counting on the company to keep growing earnings by 30%–at a minimum.

Here’s what the company reported.

For the second quarter Ctrip.com, a strong No. 1 in China’s online travel industry, reported earnings of 23 cents a share. That was two cents a share above Wall Street projections and represents year-to-year earnings per share growth of 35%.

Revenue climbed by 46% from the second quarter of 2009 to $103 million. That was above the Wall Street consensus for revenues of $98.9 million.

From there the numbers get a little disconcerting for an expensive growth stock.

The company’s guidance for the third quarter was, at 35% to 40% revenue growth, only in line with Wall Street projections of $112 million in revenues. (The company’s projected growth rate works out to $108 to $112 million in revenue.

And management raised doubts, in my mind at least, about the company’s ability to meet those goals. Growth in air ticket sales in the second quarter trailed management’s previous guidance. And the company faces significant headwinds in that part of its business starting in the third quarter.

Following the lead of Air France-KLM international and domestic airlines have cut commission rates in China.  Few airlines have been as aggressive as Air France, which cut rates to near zero but many airlines, including China’s three major airlines have cut commissions. In August Lufthansa and Air Canada joined in by cutting commissions to 1% from 3% and from 3% from 5%, respectively.

That means Ctrip.com, which generates about 40% of its revenue from air tickets will have to make up for falling commission rates from increasing ticket volume. That’s not impossible but it is hard. Ticket volume grew by 18% in China in the first six months of 2010.

I’d still like to buy shares of Ctrip.com, but the August 10 price to earnings ratio of 43.5 times projected 2010 earnings per share seemed very rich given the uncertainties in the stock. Since then the stock has dropped to $38.98 as of 3 p.m. on August 25.

Lower but still pricy considering the risk in the second quarter numbers. For now I’ll watch.

Ctrip,com is a member of my Jubak Picks 50 portfolio (https://jubakpicks.com/jubak-picks-50/  )

Full disclosure: I don’t own shares of any company mentioned in this post in my personal portfolio.